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turbance or polarity is in some manner disturbed by the 
influence of the neighbouring electric currents ; but our 
knowledge of the molecular constitution of matter is as 
yet much too limited to admit even a supposition being 
formed as to the precise manner. In permanent magnets 
of hard steel, I think that a similar polarity is effected by 
the process, whatever it may be, by which the magnetism 
is induced; that such polarity is retained for an indefinite 
period, as the hardness of the material prevents the polar- 
ised particles returning to their normal condition. 
We may conceive that a body (A) affected by magnetic 
polarity, may affect an adjacent body (B), producing a 
similar polarity, by arranging the particles of B in like 
manner as those of A as regards polar direction; that of 
the particles of A, the ponderable matter is distributed in 
one direction, the imponderable in another; but on substi- 
tuting another body (C) for B, the arrangement of particles 
may be so different, in that the imponderable is more 
attracted, that the imponderable B will exhibit phenomena 
as a magnetic bar dia-magnetic ; and we may conceive, in 
accordance with Professor Plucker’s law, that the effect of 
the dia-magnetic force on the attraction causing it, affects 
the ponderable and imponderable atoms of matter in a 
different ratio; that a certain development of magnetic 
force attracts the ponderable elements more than the im- 
ponderable, producing magnetic polarity ; that a higher 
development of magnetic force attracts the imponderable 
more than the ponderable, producing dia-magnetic polarity ; 
that in an intermediate state both the ponderable and im- 
ponderable atoms are attracted so equally, that neither 
magnetic nor dia-magnetic polarity is produced ; but, never- 
theless, such molecular disturbance is caused, that powerful 
revulsive currents are developed on the discontinuance of 
such affection of the atoms. 
